Generic code to iterate through the objects of sysvipc shared memory,message queues and semaphores. The logic to save and restore the stateof these objects will be added in the next few patches.

Right now, we return -EPERM if the user calling sys_restart() isn'tallowed to create an object with the checkpointed uid. We may preferto simply use the caller's uid in that case - but that could lead tosubtle userspace bugs? Unsure, so going for the stricter behavior.